Quantum Exceptional Points in Circuit Quantum Electrodynamics

Abstract

Recently, exceptional points (EPs) have emerged as a topic of considerable interest in the field of optics. At these points in the parameter space of an operator governing a system’s time evolution, the evolution of a system is fundamentally altered. Engineering EPs into optical systems has allowed researchers to develop a number of new devices which leverage these modified time dynamics and exhibit properties that would otherwise be unachievable. Recently, a full theory of EPs in semiclassical light-matter systems has been developed. In these systems, the interactions between radiation sources and the electromagnetic fields are described by a set of static field modes into which sources radiate. In this picture, the state of the radiation sources does not alter the structure of the field modes. This thesis reviews this theory and discusses an extension of this theory to a fully quantum mechanical theory of EPs in which radiation sources modify the structure of the field modes. As a controllable platform for simulating quantum interactions, circuit quantum electrodynamics (circuit QED) is expected to exhibit such quantum exceptional points in certain parameter regimes. We propose an experiment using the circuit QED architecture to demonstrate this newly developed quantum theory of EPs. Such an experiment will serve to validate this theory and allow future researchers to use it in the development of new quantum mechanical devices which exhibit non-unitary time evolution.